Orioles starting pitcher Wei-Yin Chen played a prominent role in the team’s playoff run in 2012. (Patrick Semansky/AP)

It didn’t happen immediately this season, but Baltimore Orioles left-hander Wei-Yin Chen slowly is emerging as the pitcher who excelled for the club in its surprising playoff run in 2012.

And that could be a huge development for a team that sits by itself — at least temporarily — atop the American League East standings.

Chen tied a season high with seven strong innings Friday night as the Orioles beat the Houston Astros, 4-3, before an excitable crowd of 28,875.

The first-place Orioles (19-14) have won seven of their last nine. Meanwhile, the Astros (11-25), baseball’s worst team, have dropped eight of 10.

After giving up eight runs in his first two starts, Chen (4-2) has yielded just 10 runs in his past five starts and has won four of five decisions.

His ERA has dropped to 3.95.

On Friday, he gave up just two runs on five hits and a walk while striking out four. Former Oriole L.J. Hoes hit a sacrifice fly in the third and Chris Carter homered in the seventh against Chen, who again succeeded by getting his breaking pitches over for strikes.

Chen was locked into a pitcher’s battle heading before the Orioles scored twice against veteran reliever Jerome Williams in the seventh.

Rookie Jonathan Schoop broke the tie with a two-out single to score J.J. Hardy. It was Schoop’s fourth RBI in the past three games.

Nick Markakis followed with a RBI double to score Schoop. Markakis had three more hits in the game, extended his hitting streak to 16. He’s hitting .354 with two homers and eight RBI in that span.

Darren O’Day threw a scoreless eighth in relief of Chen, and then closer Tommy Hunter, pitching for the third time in four nights, picked up his 11th save. In classic Hunter fashion, it wasn’t easy.

The big right-hander pitched around a leadoff double and allowed a run but induced a double play and strikeout to preserve the victory.

The Orioles scored twice in the third with two solo homers against Houston right-hander and former teammate Scott Feldman, who was activated from the disabled list Friday after dealing with right biceps tendinitis.

Steve Pearce, who is filling in at first base for the injured Chris Davis, continued his hot streak, homering just over the left field wall to tie the score at 1-1.

Three batters later, Manny Machado hit a 2-2 change-up into the bullpen beyond center field to give the Orioles the lead.